/**
 * Copyright 2017 TerraMeta Software, Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.cloudgraph.query.expr;

/**
 * Expression visitor pattern client interface.
 * 
 * @author Scott Cinnamond
 * @since 0.5.2
 * @see Expr
 */
public interface ExprVisitor {

  /**
   * The client event received when a new node is encountered.
   * 
   * @param target
   *          the target node
   * @param source
   *          the target node
   * @param level
   *          the traversal level
   * @see Expr
   */
  public void visit(Expr target, Expr source, int level);
}
